I became a Christian when I was in high school and wasn't really immersed into the Christian culture until I was in college. What that means is that right around 2000 I thought listening to Creed and P.O.D. was spiritual. I'm not saying it's not, but it's certainly no Ace Troubleshooter or Living Sacrifice.
Anyway, most of my music collection was based around hard rock/metal acts, with Metallica being the centerpiece. I also listened to Kid Rock (pre-country days), Limp Bizkit, Rob Zombie, and Godsmack. Quite a few of these compact discs came with that little black and white parental advisory image in one of the corners of the cover art.
In college I discovered that there was some pretty awesome music that was either worshipful of God or at least made by Christians speaking about life and struggles. Suddenly I was listening to Project 86, UnderOath, Pillar, and Pax217 to name a few. This also meant the demise of most of the discs from my high school days. I snapped in half probably a dozen or two discs, keeping a select few (all my Metallica remains in tact).
This isn't an uncommon phenomenon. Plenty of people have decided to do away with culture that reflected a secular life: music, movie, clothes, etc. all being nixed. But as the days, weeks, and years since a strong conviction pass by, we often begin turning toward mainstream culture. We rationalize that we're in a good place and it'll be okay to listen to music with a ton of swearing or watch a movie that shows just some brief nudity.
Or maybe we go in the other direction and become legalistic, somehow making it that throwing out the Jay-Z cd will lead to eternal salvation, calling out anyone who does not share the same conviction.
I have experienced two responses to these scenarios. First, it's a personal decision. I can watch a movie like
Braveheart and not be filled with lust from a topless scene and not have the desire to take a beastly sword to my English oppressors. That could be different for someone else, and I need to respect that. If a brother or sister in Christ says they don't feel right watching that movie, or wearing certain clothing, or whatever else, I need to act in a way that does not cause them to stumble (Romans 14:13). We should not accost each other's convictions, but honor their decisions and work out our own convictions and drawn lines with our God.
With that said, it can't be ignored that what goes in will most likely come out. Should I listen to music that excessively uses foul language and follow it up by watching
The Departed, and then accidentally drop the f-bomb in a casual conversation, I should really look at my shocked friends and say, "I have no idea where that came from!" What we put into our ears, into our eyes, into our mind and into our heart will clearly have an impact into what we put back out into the world. Philippians 4:8 says "...whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise, think about these things" (ESV). It might not be sinful to expose yourself to some mainstream culture, but we are clearly called upon to rest our mind on things of God.
Sometimes it's really simple. This summer I've struggled with regularly reading my bible and have mostly listened to country, alternative, classic rock, and talk radio. This week I've tried to focus on reading a chapter of the Bible each morning while listening to either my Christian Pandora station or Christian radio. Now neither action has granted me eternal salvation. I've already received that through the bloody death on the cross by Jesus. However, if we will be known by our fruits, it's a good idea to plant good seeds (Matthew 7: 15-20).